1型强直性肌营养不良症（DM1）是最常见的成人肌营养不良症。DM1由强直性肌营养不良蛋白激酶（DMPK）基因的(CTG)n重复序列异常扩增引起,目前尚不能治愈。我们前期研究利用人工特异性RNA内切酶（ASREs）识别并降解DM1病人细胞中致病DMPK的mRNAs，减少细胞核内RNA聚集及纠正多个基因的异常剪接（Molecular Therapy, 2014）。但如何提高ASREs的特异性，减少脱靶现象，亟待解决。在前期研究的基础上结合我们深厚的RNA研究背景（Nat Struct Mol Biol, 2011），本项目将在第一代ASREs的基础上进行优化，筛选出具有最佳活性的ASREs，探明ASREs能否降解致病基因DMPK mRNA以及对DM1细胞的影响；并系统性分析其对DM1细胞整个转录组的影响。本项目的顺利实施将为ASREs药物的研制与开发打下基础，为DM1提供一种新的治疗策略。

Myotonic dystrophy type 1 (DM1) is the most common form of adult muscular dystrophy. DM1 is caused by the progressive expansion of (CTG) triplet in the 3' untranslated region (UTR) of DMPK (dystrophia myotonica-protein kinase) gene. Although some symptoms of DM1 can be treated and alleviated, currently there is no cure for this disease. Our previous data showed the first generation of engineering site-specific RNA endonucleases (ASREs) can specifically degrade the pathogenic DMPK mRNAs, significantly decreased the number of nuclear foci and can reverse the mis-splicing of many genes affected in DM1 cells (Molecular Therapy, 2014). But how to increase the binding specificity and reduce off-target effect? Based on our preliminary results and our research background on RNA (Nat Struct Mol Biol, 2011), we will carry out experiments to optimize the first generation of ASREs to select for enzymes with optimal activities. And we will test if they can indeed cleave pathogenic DMPK mRNAs and determine the cellular consequence of different ASREs in DM1 cells; We will further systematically analyze the genomic consequence and off-target effect of ASREs treatment. This study will lay a solid foundation for the drug development of ASREs. Collectively, ASREs will open a new door that leads to the treatment of DM1 through gene therapy approach.